1. Field of the Invention
The present invention relates to a rotary compressor having a lubricating oil supplying device. More particularly, it relates to an improvement in feeding of oil to a thrust-bearing surface which is in slide-contact with an eccentric part of a rotary shaft.
2. Description of Prior Art
FIG. 1 is a cross-sectional view of an important part of a conventional rotary compressor as disclosed in Japanese Unexamined Patent Publication No. 106089/1981.
In FIG. 1, a reference numeral 1 designates a cylinder and a numeral 2 designates a rotary shaft which is adapted to be rotated in the cylinder and having an eccentric part 3 formed integrally with it. The rotary shaft is driven by a motor (not shown) provided at the upper side on the drawing. A rolling piston 4 is fitted on the outer circumferential surface of the eccentric part 3 to eccentrically rotate in the cylinder 1 in accordance with the rotation of the rotary shaft. A reference numeral 5 designates a main bearing plate for supporting a part of the rotary shaft 2 extending toward the motor and a numeral 6 designates a sub-bearing plate for supporting a part of the rotary shaft 2 extending in the direction opposite the motor with respect to the eccentric part 3, both the bearing plates being placed at both sides of the cylinder 1 to keep the inside of the cylinder in a hermetic condition. A numeral 7 designates vanes whose extreme ends are usually in contact with the rolling piston 4 under a desired pressure applied by means of compression springs, a numeral 8 designates a thrust-bearing surface formed between the eccentric part 3 and the sub-bearing plate 6, a symbol A designates a conduit formed in the axial center portion of the rotary shaft 2 to feed lubricating oil for circulation in the compressor device, a symbol a indicates oil feeding passages formed in the rotary shaft 2 in the radial direction from the conduit, and a symbol B indicates a compression chamber.
In the conventional rotary compressor having the construction as above-mentioned, there is a disadvantage such that since there is no facility to keep the lubricating oil in the thrust-bearing surface, when the compressor is to be re-started after the operation of the compressor has been paused for a long term, there arises a shortage of oil in the thrust-bearing surface 8, with the result that friction in the thrust-bearing surface frequently occurs, whereby much input power is required at the time of restarting of the compressor.